The present invention relates to a pneumatic bias tire incorporating a carcass layer utilizing an aromatic polyamide fiber cord, which can exhibit remarkable steering stability and high-speed durability.
Pneumatic bias tires utilizing an aromatic fiber cord for carcass ply cords are known per se. For instance, Japanese patent publication No. 57-12586 discloses an example of such tires. Aromatic polyamide fiber cords have a high tenacity and a high modulus of elasticity, and the bias tire incorporating such cords, disclosed in the above patent publication, can exhibit a remarkable tire performance including a remarkable steering stability in particular and, because of this, has already been industrially produced particularly in the product form of pneumatic tires for racing cars.
Although aromatic polyamide fiber cords can exhibit highly desirable cord characteristics as above, their bondability with or adhesion to rubber is relatively limited, and due to this, their characteristic of having a high modulus of elasticity tends to take a negative or disadvantageous effect in tires and cause them to undergo rupture through buckling. Therefore, particularly in the cases of racing-car tires which are run under severe service conditions of for example running at a super high speed, problems are likely such as separation of carcass ply cords and bursting, and the known tires incorporating an aromatic fiber cord tend to involve a difficulty to do with the high-speed durability.